A major problem encountered by both experienced and inexperienced divers during diving is so-called dive stress, in particular pre-dive stress. This dive stress increases the likelihood of mistakes being made prior to and during diving, mistakes which can have fatal consequences. The chance of a panic situation under water is also increased considerably by this dive stress.
In practice, it is found that most divers dive only once or twice a year. These are the divers at greatest risk. It has been found that when such an inexperienced diver is in distress or in danger he has only three seconds in which it is possible to take action. In the first second the distress or danger is perceived, in the second second the diver becomes aware of the problem and his position, and in the third second the diver is in a panic. The most common reaction of such divers is to swim as fast as possible towards the surface, with all the risks this involves.
In a panic situation inexperienced divers are found to be incapable of any coordinated movement, for example in order to activate an alarm device. The known alarm devices for use as diving aids are therefore found to be inadequate.
In this connection reference is made to FR-A-2,695,747. This French patent application discloses an alarm device for attaching to the wrist. This device comprises two parts that are rotatable relative to each other and can be locked relative to each other by means of a locking pin. This locking pin has to be removed in order to activate the alarm device.
FR-A-2,755,023 also discloses an alarm device, which comprises a housing with a battery and sound-generating means. The housing comprises a push-button for activating the alarm device. This alarm device is attached to an eye present on the housing.
It has been found that a diver who is in a panic is incapable of removing a locking pin in a controlled manner or locating and pressing a push-button on a trailing device. Divers also very often wear gloves during diving, which makes such actions even more difficult. Furthermore, a fully equipped diver has very limited freedom of movement.